Semiconductor device

ABSTRACT

A semiconductor device includes a fin-shaped silicon layer on a silicon substrate and a first insulating film around the fin-shaped silicon layer. A pillar-shaped silicon layer resides on the fin-shaped silicon layer. A gate electrode and gate insulating film surround the pillar-shaped silicon layer and a gate line is connected to the gate electrode and extends in a direction orthogonally intersecting the fin-shaped silicon layer. A first diffusion layer resides in an upper portion of the pillar-shaped silicon layer and a second diffusion layer resides in an upper portion of the fin-shaped silicon layer and a lower portion of the pillar-shaped silicon layer.

RELATED APPLICATIONS

This application is a continuation patent application of U.S. patentapplication Ser. No. 14/449,614, filed Aug. 1, 2014, now U.S. Pat. No.9,035,388, which is a continuation of U.S. patent application Ser. No.14/044,501, filed Oct. 2, 2013, now U.S. Pat. No. 8,829,619, whichclaims benefit of Provisional U.S. Patent Application Ser. No.61/711,329, filed Oct. 9, 2012 pursuant to 35 U.S.C. §119(e), the entirecontents of which are hereby incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a semiconductor device.

2. Description of the Related Art

Increasingly higher degrees of integration continue to be achieved insemiconductor integrated circuits, especially integrated circuits thatuse MOS transistors. With the increase in the degree of integration, MOStransistors used in integrated circuits have scaled down to thenanometer order. As the miniaturization of the MOS transistors proceeds,it is becoming increasingly difficult to suppress leak current and toreduce the area occupied by the circuits while maintaining a requiredamount of current. In order to address these challenges, surroundinggate transistors (referred to as “SGTs” hereinafter) in which a source,a gate, and a drain are arranged in a direction perpendicular to asubstrate and a gate electrode surrounds a pillar-shaped semiconductorlayer have been proposed (for example, refer to Japanese UnexaminedPatent Application Nos. 2-71556, 2-188966, and 3-145761).

According to a conventional method for producing SGTs, a contact hole inan upper portion of a silicon pillar is formed separately from a contacthole in a lower portion of the silicon pillar and on a planar siliconlayer since the depths of these contacts are different from each other(for example, refer to Japanese Unexamined Patent ApplicationPublication No. 2012-004244). Since the contact holes are formedseparately, the number of steps is increased.

While the contact hole in the upper portion of a silicon pillar isformed separately from the contact hole in the lower portion of thesilicon pillar and on the planar silicon layer, excessively etching thecontact hole in the upper portion of the silicon pillar may result inetching of a gate electrode. If etching is insufficient, there is apossibility that the silicon pillar upper portion is insulated from thecontact.

Since the contact hole in the lower portion of the silicon pillar and onthe planar silicon layer is deep, it is difficult to fill the contacthole. Moreover, it is difficult to form a deep contact hole.

According to a conventional method for producing SGTs, a silicon pillarin which a nitride film hard mask is formed to have a pillar shape isformed, a diffusion layer is formed in a lower portion of the siliconpillar, a gate material is then deposited, planarized and etched back,and an insulating film side wall is formed on a side wall of the siliconpillar and the nitride film hard mask. Then a resist pattern for a gateline is formed, the gate material is etched, the nitride film hard maskis removed, and a diffusion layer is formed in an upper portion of thesilicon pillar (for example, refer to Japanese Unexamined PatentApplication No. 2009-182317).

In this method, in the cases where intervals between silicon pillars arenarrow and a thick gate material must be deposited between the siliconpillars, holes called voids are sometimes formed between the siliconpillars. Formation of voids leads to formation of holes in the gatematerial after etch back. When an insulating film is deposited to formthe insulating film side wall, the insulating film is deposited in thevoids. Accordingly, it becomes more difficult to work with the gatematerial.

To address this, a proposal has been made (for example, refer to B.Yang, K. D. Buddharaju, S. H. G. Teo, N. Singh, G. D. Lo, and D. L.Kwong, “Vertical Silicon-Nanowire Formation and Gate-All-Around MOSFET”,IEEE Electron Device Letters, VOL. 29, No. 7, July 2008, pp. 791-794) inwhich a gate oxide film is formed after formation of a silicon pillar, athin polysilicon is deposited, a resist covering an upper portion of thesilicon pillar and for forming a gate line is then formed, a gate lineis etched, an oxide film is then thickly deposited, the upper portion ofthe silicon pillar is exposed, the thin polysilicon on the upper portionof the silicon pillar is removed, and the thick oxide film is removed bywet etching.

However, a method in which a metal is used in the gate electrode is notdescribed. Moreover, a resist covering an upper portion of the siliconpillar and for forming a gate line must be formed and the upper portionof the silicon pillar must be covered; thus, this method is not aself-aligned process.

In order to decrease the parasitic capacitance between the gate line andthe substrate, a conventional MOS transistor uses a first insulatingfilm. For example, in a FINFET (High performance 22/20 nm FinFET CMOSdevices with advanced high-K/metal gate scheme, IEDM 2010 CC. Wu, et.al, 27.1.1-27.1.4), a first insulating film is formed around onefin-shaped semiconductor layer and is etched back to expose thefin-shaped semiconductor layer so as to decrease the parasiticcapacitance between the gate line and the substrate. Thus, the firstinsulating film must be used to decrease the parasitic capacitancebetween the gate line and the substrate in the SGT also. Since a SGTincludes a pillar-shaped semiconductor layer in addition to a fin-shapedsemiconductor layer, adjustment must be made for forming thepillar-shaped semiconductor layer.

SUMMARY

Accordingly, an object is to provide a SGT in which a parasiticcapacitance between a gate line and a substrate is reduced, no contactis formed in an upper portion of a pillar-shaped silicon layer, and ametal wire is directly connected to the upper portion of thepillar-shaped silicon layer, and a structure of a SGT obtained by themethod.

A semiconductor device according to the present invention includes afin-shaped silicon layer on a silicon substrate; a first insulating filmaround the fin-shaped silicon layer; a pillar-shaped silicon layer onthe fin-shaped silicon layer; a gate insulating film formed around thepillar-shaped silicon layer; a gate electrode around the gate insulatingfilm; a gate line connected to the gate electrode and extending in adirection orthogonally intersecting the fin-shaped silicon layer; afirst diffusion layer in an upper portion of the pillar-shaped siliconlayer; and a second diffusion layer in an upper portion of thefin-shaped silicon layer and a lower portion of the pillar-shapedsilicon layer.

The semiconductor device also includes a gate electrode having amultilayered structure constituted by a metal film and a polysiliconfilm formed around the gate insulating film. The thickness of thepolysilicon film is smaller than the width of the pillar-shaped siliconlayer.

The depth of the first contact is smaller than the height of thepillar-shaped silicon layer.

A method for producing a semiconductor device according to the presentinvention includes a first step of forming a fin-shaped silicon layer ona silicon substrate, forming a first insulating film around thefin-shaped silicon layer, and forming a pillar-shaped silicon layer inan upper portion of the fin-shaped silicon layer; a second step offorming a gate insulating film around the pillar-shaped silicon layer, agate electrode around the gate insulating film, and a gate lineconnected to the gate electrode; a third step of forming a firstdiffusion layer in an upper portion of the pillar-shaped silicon layerand a second diffusion layer in a lower portion of the pillar-shapedsilicon layer and an upper portion of the fin-shaped silicon layer; afourth step of forming a first silicide and a second silicide on thefirst diffusion layer and the second diffusion layer; and after thefourth step, a fifth step of depositing an interlayer insulating film,planarizing and etching-back the interlayer insulating film to expose anupper portion of the pillar-shaped silicon layer, forming a fifth resistfor forming a first contact after the upper portion of the pillar-shapedsilicon layer is exposed, etching the interlayer insulating film to forma contact hole, depositing a metal to form the first contact on thesecond silicide, forming a sixth resist for forming a metal wire, andperforming the etching to form the metal wire.

In the first step, a width of the pillar-shaped silicon layer is equalto a width of the fin-shaped silicon layer.

In the first step, a first resist for forming the fin-shaped siliconlayer is formed on the silicon substrate, the silicon substrate isetched to form the fin-shaped silicon layer, and the first resist isremoved; and a first insulating film is deposited around the fin-shapedsilicon layer and etched-back to expose an upper portion of thefin-shaped silicon layer, a second resist is formed so as toorthogonally intersect the fin-shaped silicon layer, the fin-shapedsilicon layer is etched, and the second resist is removed so that aportion where the fin-shaped silicon layer orthogonally intersects thesecond resist forms the pillar-shaped silicon layer.

In the second step, the gate insulating film is formed around thepillar-shaped silicon layer, a metal film and a polysilicon film havinga thickness smaller than a width of the pillar-shaped silicon layer areformed around the gate insulating film, a third resist for forming agate line is formed, and anisotropic etching is performed to form thegate line. A fourth resist is deposited, the polysilicon film at anupper side wall of the pillar-shaped silicon layer is exposed, theexposed polysilicon film is removed by etching, the fourth resist isremoved, the metal film is removed by etching, and a gate electrodeconnected to the gate line is formed.

Advantageous Effects of Invention

According to the present invention, a method for producing a SGT inwhich a parasitic capacitance between a gate line and a substrate isreduced, no contact is formed in an upper portion of a pillar-shapedsilicon layer, and a metal wire is directly connected to the upperportion of the pillar-shaped silicon layer, and a structure of a SGTobtained by the method can be provided.

Since the metal wire is directly connected to the upper portion of thepillar-shaped silicon layer, a step of forming a contact in the upperportion of the pillar-shaped silicon layer is no longer needed.

Since the metal wire is directly connected to the upper portion of thepillar-shaped silicon layer, the depth of the contact hole for a firstcontact can be decreased. Thus, the contact hole can be easily formedand filled with a metal.

Moreover, since production of the fin-shaped silicon layer, the firstinsulating film, and the pillar-shaped silicon layer is based on theconventional methods for producing FINFETs, the production is easy.

Moreover, a self-aligned process is realized through the second step inwhich the gate insulating film is formed around the pillar-shapedsilicon layer, a metal film and a polysilicon film having a thicknesssmaller than a width of the pillar-shaped silicon layer are formedaround the gate insulating film, a third resist for forming a gate lineis formed, and anisotropic etching is performed to form the gate line. Afourth resist is deposited, the polysilicon film at an upper side wallof the pillar-shaped silicon layer is exposed, the exposed polysiliconfilm is removed by etching, the fourth resist is removed, the metal filmis removed by etching, and a gate electrode connected to the gate lineis formed. Since the method involves a self-aligned process, higherintegration is possible.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 1( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 1( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 2( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 2( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 2( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 3( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 3( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 3( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 4( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 4( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 4( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 5( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 5( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 5( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 6( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 6( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 6( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 7( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 7( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 7( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 8( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 8( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 8( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 9( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 9( b) is a cross-sectional view taken along linex-x′ in (a). FIG. 9( c) is a cross-sectional view taken along line y-y′in (a).

FIG. 10( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 10( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 10( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 11( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 11( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 11( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 12( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 12( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 12( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 13( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 13( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 13( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 14( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 14( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 14( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 15( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 15( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 15( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 16( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 16( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 16( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 17( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 17( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 17( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 18( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 18( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 18( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 19( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 19( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 19( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 20( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 20( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 20( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 21( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 21( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 21( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 22( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 22( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 22( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 23( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 23( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 23( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 24( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 24( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 24( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 25( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 25( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 25( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 26( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 26( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 26( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 27( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 27( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 27( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 28( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 28( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 28( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 29( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 29( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 29( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 30( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 30( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 30( c) is a cross-sectional view taken along liney-y′ in (a).

FIG. 31( a) is a plan view of a semiconductor device according to thepresent invention. FIG. 31( b) is a cross-sectional view taken alongline x-x′ in (a). FIG. 31( c) is a cross-sectional view taken along liney-y′ in (a).

DETAILED DESCRIPTION

Production steps for forming a SGT structure according to an embodimentof the present invention are described below with reference to FIGS. 2to 31.

First, a production method in which a fin-shaped silicon layer 103 isformed on a silicon substrate 101, a first insulating film 104 is formedaround the fin-shaped silicon layer 103, and a pillar-shaped siliconlayer 106 is formed in an upper portion of the fin-shaped silicon layer103 is described. As shown in FIG. 2, a first resist 102 for forming afin-shaped silicon layer is formed on the silicon substrate 101.

As shown in FIG. 3, the fin-shaped silicon layer 103 is formed byetching the silicon substrate 101. Although a resist is used this timeas a mask to form a fin-shaped silicon layer, a hard mask such as anoxide film or a nitride film may alternatively be used.

As shown in FIG. 4, the first resist 102 is removed.

As shown in FIG. 5, the first insulating film 104 is deposited aroundthe fin-shaped silicon layer 103. An oxide film formed by high-densityplasma or an oxide film formed by low-pressure chemical vapor depositionmay be used as the first insulating film, for example.

As shown in FIG. 6, the first insulating film 104 is etched back toexpose an upper portion of the fin-shaped silicon layer 103. The stepsup to and including this are the same as those of the method forproducing a fin-shaped silicon layer in Non Patent Literature 2.

As shown in FIG. 7, a second resist 105 is formed so as to orthogonallyintersect the fin-shaped silicon layer 103. The part where thefin-shaped silicon layer 103 and the second resist 105 orthogonallyintersect is the portion that will form a pillar-shaped silicon layer.Since a line-shaped resist can be used, the possibility of breaking ofthe resist after patterning is low and the process becomes stable.

As shown in FIG. 8, the fin-shaped silicon layer 103 is etched. Theportion where the fin-shaped silicon layer 103 and the second resist 105orthogonally intersect forms the pillar-shaped silicon layer 106.Accordingly, the width of the pillar-shaped silicon layer 106 is equalto the width of the fin-shaped silicon layer. Thus, a structure isformed in which the pillar-shaped silicon layer 106 is formed in theupper portion of the fin-shaped silicon layer 103 and the firstinsulating film 104 is formed around the fin-shaped silicon layer 103.

As shown in FIG. 9, the second resist 105 is removed.

Next, a production method is described in which a gate insulating film107 is formed around the pillar-shaped silicon layer 106, a metal film108 and a polysilicon film 109 having a thickness smaller than the widthof the pillar-shaped silicon layer are formed around the gate insulatingfilm 107, a third resist 110 for forming a gate line 111 b is formed andanisotropically etched to form the gate line 111 b, a fourth resist 112is then deposited, the polysilicon film 109 on the upper side wall ofthe pillar-shaped silicon layer 106 is exposed, the exposed polysiliconfilm 109 is removed by etching, the fourth resist 112 is removed, themetal film 108 is removed by etching, and a gate electrode 111 aconnected to the gate line 111 b is formed.

As shown in FIG. 10, the gate insulating film 107 is formed around thepillar-shaped silicon layer 106, and the metal film 108 and thepolysilicon film 109 are formed around the gate insulating film 107.During this process, a thin polysilicon film 109 is used. Accordingly,formation of voids in the polysilicon film can be prevented. Thethickness of the thin polysilicon film 109 is preferably 20 nm or less.The metal film 108 may be composed of any metal, such as titaniumnitride, that is used in semiconductor processes and sets the thresholdvoltage of a transistor. The gate insulating film 107 may be a film,such as an oxide film, an oxynitride film, or a high-k dielectric film,used in semiconductor processes.

As shown in FIG. 11, the third resist 110 for forming the gate line 111b is formed. In this embodiment, the height of the resist is describedto be higher than the pillar-shaped silicon layer. The smaller the gateline width, the easier it is for polysilicon in the upper portion of thepillar-shaped silicon layer to be exposed. The height of the resist maybe lower than the pillar-shaped silicon layer.

As shown in FIG. 12, the polysilicon film 109 and the metal film 108 areetched. The gate electrode 111 a and the gate line 111 b are formed.During this process, if the resist on the upper portion of thepillar-shaped silicon layer is thin or the polysilicon in the upperportion of the pillar-shaped silicon layer is exposed, the upper portionof the pillar-shaped silicon layer may become etched during etching. Insuch a case, the height of the pillar-shaped silicon layer at the timeof formation of the pillar-shaped silicon layer is preferably equal tothe sum of the desired height of the pillar-shaped silicon layer and theheight of the portion removed during gate line etching. Accordingly, theproduction steps of the present invention are self-aligned processes.

As shown in FIG. 13, the third resist is removed.

As shown in FIG. 14, the fourth resist 112 is deposited and thepolysilicon film 109 on the upper side wall of the pillar-shaped siliconlayer 106 is exposed. Preferably, resist etch back is employed.Alternatively, a coating film such as a spin-on-glass may be used.

As shown in FIG. 15, the exposed polysilicon film 109 is removed byetching. Isotropic dry etching is preferably employed.

As shown in FIG. 16, the fourth resist 112 is removed.

As shown in FIG. 17, the metal film 108 is removed by etching so thatthe metal film 108 remains on the side wall of the pillar-shaped siliconlayer 106. Isotropic etching is preferably employed. The metal film 108and the polysilicon film 109 on the side wall of the pillar-shapedsilicon layer 106 form the gate electrode 111 a. Accordingly, this is aself-aligned process.

This ends the description of the production method in which a gateinsulating film 107 is formed around the pillar-shaped silicon layer106, a metal film 108 and a polysilicon film 109 having a thicknesssmaller than the width of the pillar-shaped silicon layer are formedaround the gate insulating film 107, a third resist 110 for forming agate line 111 b is formed and anisotropically etched to form the gateline 111 b, a fourth resist 112 is then deposited, the polysilicon film109 on the upper side wall of the pillar-shaped silicon layer 106 isexposed, the exposed polysilicon film 109 is removed by etching, thefourth resist 112 is removed, the metal film 108 is removed by etching,and a gate electrode 111 a connected to the gate line 111 b is formed.

Next, a production method is described in which a first diffusion layer114 is formed in an upper portion of the pillar-shaped silicon layer 106and a second diffusion layer 113 is formed in a lower portion of thepillar-shaped silicon layer 106 and an upper portion of the fin-shapedsilicon layer 103.

As shown in FIG. 18, arsenic is implanted to form the first diffusionlayer 114 and the second diffusion layer 113. In the case of pMOS, boronor boron fluoride is implanted.

As shown in FIG. 19, a nitride film 115 is deposited and a heattreatment is performed. An oxide film may be used instead of a nitridefilm.

This ends the description of the production method in which a firstdiffusion layer 114 is formed in an upper portion of the pillar-shapedsilicon layer 106 and a second diffusion layer 113 is formed in a lowerportion of the pillar-shaped silicon layer 106 and an upper portion ofthe fin-shaped silicon layer 103.

Next, a production method is described in which a first silicide 118 anda second silicide 117 are formed on the first diffusion layer 114 andthe second diffusion layer 113.

As shown in FIG. 20, the nitride film 115 is etched so that the nitridefilm 115 remains as a side wall and the gate insulating film 107 isetched to form nitride film side walls 116 a and 116 b.

Next, as shown in FIG. 21, a metal is deposited and heat-treated andunreacted metal is removed so as to form the first silicide 118, thesecond silicide 117, and a silicide 119 on the first diffusion layer114, the second diffusion layer 113, and the gate line 111 b. In thecase where the upper portion of the gate electrode 111 a is exposed, asilicide 120 is formed in an upper portion of the gate electrode 111 a.

Since the polysilicon film 109 is thin, the gate line 111 b tends tohave a multilayered structure constituted by the metal film 108 and thesilicide 119. Since the silicide 119 and the metal film 108 come intodirect contact with each other, the resistance can be decreased.

This ends the description of the production method for forming the firstsilicide 118 and the second silicide 117 on the first diffusion layer114, the second diffusion layer 113, and the gate line 111 b.

Next, a production method in which an interlayer insulating film 121 isdeposited, planarized, and etched back to expose an upper portion of thepillar-shaped silicon layer 106, a fifth resist 122 for forming a firstcontact 127 is formed after the upper portion of the pillar-shapedsilicon layer 106 is exposed, the interlayer insulating film 121 isetched to form a contact hole 123, a metal 130 is deposited to form afirst contact 127 on the second silicide 117, sixths resists 131, 132,and 133 for forming metal wires 134, 135, and 136 are formed, andetching is performed to form the metal wires 134, 135, and 136.

As shown in FIG. 22, a contact stopper 140 such as a nitride film isformed and the interlayer insulating film 121 is formed.

As shown in FIG. 23, etch-back is performed to expose the contactstopper 140 on the pillar-shaped silicon layer 106.

As shown in FIG. 24, a fifth resist 122 for forming contact holes 123and 124 is formed.

As shown in FIG. 25, the interlayer insulating film 121 is etched toform the contact holes 123 and 124.

As shown in FIG. 26, the fifth resist 122 is removed.

As shown in FIG. 27, the contact stopper 140 is etched so as to removethe contact stopper 140 under the contact holes 123 and 124 and thecontact stopper on the pillar-shaped silicon layer 106.

As shown in FIG. 28, the metal 130 is deposited to form first contacts127 and 129. Since the metal wire and the upper portion of thepillar-shaped silicon layer are directly connected to each other duringthis process, the step of forming a contact in the upper portion of thepillar-shaped silicon layer is no longer necessary. Moreover, since thedepth of the contact hole for forming a first contact can be decreased,it is easier to form a contact hole and to fill the contact hole with ametal.

As shown in FIG. 29, the sixths resists 131, 132, and 133 for formingmetal wires are formed.

As shown in FIG. 30, the metal 130 is etched to form the metal wires134, 135, and 136.

As shown in FIG. 31, the sixths resists 131, 132, and 133 are removed.

This ends the description of the production method in which theinterlayer insulating film 121 is deposited, planarized, and etchedback, an upper portion of the pillar-shaped silicon layer 106 isexposed, a fifth resist 122 for forming a first contact 127 is formedafter the upper portion of the pillar-shaped silicon layer 106 isexposed, a contact hole 123 is formed by etching the interlayerinsulating film 121, a first contact 127 is formed on the secondsilicide 117 by depositing a metal 130, and sixths resists 131, 132, and133 for forming metal wires 134, 135, and 136 are formed, and etching isperformed to form the metal wires 134, 135, and 136.

This ends the description of a method for producing a SGT in which aparasitic capacitance between a gate line and a substrate is reduced, nocontact is formed in an upper portion of a pillar-shaped silicon layer,and a metal wire is directly connected to the upper portion of thepillar-shaped silicon layer.

FIG. 1 shows a structure of a semiconductor device obtained through theproduction method described above. As shown in FIG. 1, the semiconductordevice includes a fin-shaped silicon layer 103 formed on a siliconsubstrate 101, a first insulating film 104 formed around the fin-shapedsilicon layer 103, a pillar-shaped silicon layer 106 formed on thefin-shaped silicon layer 103 having a width equal to the width of thepillar-shaped silicon layer 106, a gate insulating film 107 formedaround the pillar-shaped silicon layer 106, a gate electrode 111 aformed around the gate insulating film 107, a gate line 111 b extendingin a direction orthogonally intersecting the fin-shaped silicon layer103 and being connected to the gate electrode 111 a, a first diffusionlayer 114 formed in an upper portion of the pillar-shaped silicon layer106, a second diffusion layer 113 formed in an upper portion of thefin-shaped silicon layer 103 and a lower portion of the pillar-shapedsilicon layer 106, a first silicide 118 formed in an upper portion ofthe first diffusion layer 114, a second silicide 117 formed in an upperportion of the second diffusion layer 113, a first contact 127 formed onthe second silicide 117, a first metal wire 135 formed on the firstsilicide 118, and a second metal wire 134 formed on the first contact127.

The semiconductor device also includes a gate electrode 111 a which hasa multilayered structure constituted by a metal film 108 and apolysilicon film 109 formed around the gate insulating film 107. Thethickness of the polysilicon film 109 is smaller than the width of thepillar-shaped silicon layer 106.

The depth of the first contact 127 is smaller than the height of thepillar-shaped silicon layer 106. Since the depth of the first contact127 is small, the first contact resistance can be decreased.

It should be noted that various embodiments and modifications arepossible without departing from the spirit and scope of the presentinvention in a broad sense. Moreover, the embodiments described aboveare for explaining examples of the present invention and do not limitthe scope of the present invention.

For example, a method for producing a semiconductor device in whichp-type (p+ type is also included) and n-type (n+ type is also included)are reversed from that described in the embodiments described above, anda semiconductor device obtained by such a method are also within thetechnical scope of the present invention.

The invention claimed is:
 1. A semiconductor device comprising: afin-shaped silicon layer on a silicon substrate; a first insulating filmaround the fin-shaped silicon layer; a pillar-shaped silicon layer onthe fin-shaped silicon layer; a gate insulating film around thepillar-shaped silicon layer; a gate electrode around the gate insulatingfilm; a gate line connected to the gate electrode and extending in adirection orthogonally intersecting the fin-shaped silicon layer; afirst diffusion layer in an upper portion of the pillar-shaped siliconlayer; a second diffusion layer in an upper portion of the fin-shapedsilicon layer and a lower portion of the pillar-shaped silicon layer; afirst silicide in an upper portion of the first diffusion layer; a firstmetal wire on the first silicide; and a nitride film sidewall around asidewall of an upper portion of the pillar-shaped silicon layer.